JP2008042797A - Solid-state imaging element cover and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging element cover, having an optical low-pass filter which reduces damage to a solid-state imaging element caused by α rays while achieving reduction in size, height and cost, and an imaging device. <P>SOLUTION: There are obtained an imaging device 10 and a solid-state imaging element cover 40 which generates less α rays and prevents the damage to the solid-state imaging element 1, wherein a Z-cut crystal plate 3 made of single crystal having less impurities such as heavy metal is provided to seal a package 2. The two-point separation optical low-pass filter 200 is constituted by using a birefringent plate 50, thereby, achieving small number of components and simple structure, and facilitating the manufacturing. Consequently, reduction in size, height and cost of the solid-state imaging element cover 40 and the imaging device 10 can be achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state image sensor cover and an imaging apparatus used for a digital still camera, a digital video camera, and the like.

An imaging device is used for a digital still camera, a digital video camera, and the like. These portable digital devices are becoming smaller and cheaper. Accordingly, there is a demand for downsizing, low profile, and low price of the imaging apparatus.
The imaging apparatus includes a plurality of components, and includes a solid-state imaging device, a package for protecting the solid-state imaging device from the external environment, a solid-state imaging device cover for sealing the package, and the like (see Patent Document 1).
In addition, an optical low-pass filter that suppresses a spatial high-frequency component included in a captured image has become necessary due to an improvement in the element density of the solid-state imaging device.
There is known a configuration in which a diffraction grating as an optical low-pass filter is incorporated in an imaging device and the number of parts is reduced as a whole digital device (see Patent Document 2 and Patent Document 3).

JP-A-9-69618 (Page 4, FIG. 3) Japanese Patent No. 2968357 (pages 3 and 4, FIG. 6) Japanese Patent Laid-Open No. 5-273501 (2nd page, FIG. 2)

Glass is used for the solid-state image sensor cover that seals the package. As the glass, borosilicate glass, soda glass or the like is used. In recent years, α-rays are generated from a small amount of heavy metal contained in these glasses, causing a problem of causing damage to the solid-state imaging device.
An object of the present invention is to obtain a solid-state imaging device cover and an imaging apparatus provided with an optical low-pass filter that prevents damage to the solid-state imaging device due to α rays while corresponding to downsizing, low profile, and low price. is there.

  The solid-state image sensor cover of the present invention is a solid-state image sensor cover that seals a package in which the solid-state image sensor is housed, and the solid-state image sensor cover has a Z-cut crystal plate, and the light of the Z-cut crystal plate An optical low-pass filter is provided on the incident surface.

  According to the present invention, the Z-cut quartz plate made of a single crystal with few impurities such as heavy metals is provided as a solid-state image sensor cover for sealing the package. A prevented solid-state image sensor cover is obtained.

In the present invention, the optical low-pass filter is preferably a birefringent plate.
In the present invention, in addition to the above-described effect, the birefringent plate constitutes a two-point separation optical low-pass filter. Therefore, the number of parts is small, the structure is simple, and the manufacture is facilitated. Therefore, it is possible to reduce the size, the height, and the price of the solid-state image sensor cover.

In the present invention, the optical low-pass filter includes a horizontal direction separation birefringence plate and a vertical direction separation birefringence plate, and is ¼ between the horizontal direction separation birefringence plate and the vertical direction separation birefringence plate. A wave plate is preferably arranged.
In the present invention, in addition to the above-described effect, the four-point separation optical low-pass filter is constituted by the two birefringent plates and the quarter-wave plate, so that a solid-state imaging device cover in which more spatial high-frequency components are suppressed. Is obtained.

In the present invention, the optical low-pass filter preferably includes a diffraction grating.
In the present invention, since the optical low-pass filter is constituted by the diffraction grating, the number of parts is small, the structure is simple, and the manufacture is facilitated. Therefore, it is possible to reduce the size, the height, and the price of the solid-state image sensor cover.

In the present invention, the diffraction grating has irregularities with a periodic cross-sectional shape, and includes a convex portion having a first refractive index and a concave portion having a second refractive index different from the first refractive index. The thickness of the convex portion and the thickness of the concave portion are preferably set such that the diffraction efficiency in the visible light region is substantially constant.
In this invention, the diffraction efficiency is kept substantially constant for each wavelength in the visible light region. Accordingly, the diffraction grating functions as an optical low-pass filter that can extract a constant diffracted light intensity with respect to the incident light intensity at each wavelength, and a solid-state imaging device cover that can faithfully reproduce the color tone of the subject in the visible light region is obtained.

In this invention, it is preferable that the said convex part contains a silicon dioxide and the said recessed part contains a titanium dioxide or a tantalum pentoxide.
In the present invention, since a dielectric material having excellent durability is used as a material for forming the diffraction grating, a highly reliable solid-state imaging device cover can be obtained.

In the present invention, it is preferable that the convex portion contains an ultraviolet curable resin or a thermosetting resin, and the concave portion contains titanium dioxide or tantalum pentoxide.
In this invention, since the convex part contains resin, it can respond to the price reduction of a solid-state image sensor cover.

In the present invention, it is preferable that the optical low-pass filter includes two diffraction gratings, a quarter-wave plate is disposed between the diffraction gratings, and the diffraction directions of the diffraction gratings are substantially orthogonal to each other.
In the present invention, since the diffraction directions of the two diffraction gratings are orthogonal to each other, a four-point separation optical low-pass filter is formed, and a solid-state image sensor cover having a higher-performance optical low-pass filter is obtained.

In the present invention, the optical low-pass filter includes a birefringent plate and a quarter-wave plate, and the quarter-wave plate is disposed between the diffraction grating and the birefringent plate. It is preferable that the refraction direction and the diffraction direction of the diffraction grating are substantially orthogonal.
According to the present invention, a four-point separation optical low-pass filter in which the birefringence direction and the diffraction direction are substantially orthogonal to each other is configured, and a solid-state imaging device cover having a higher-performance optical low-pass filter is obtained.

  The imaging apparatus of the present invention includes a package that houses the solid-state imaging device, and a solid-state imaging device cover that seals the package. The solid-state imaging device cover includes a Z-cut quartz plate, and the Z-cut quartz plate An optical low-pass filter is provided on the incident surface.

  According to the present invention, the Z-cut quartz plate made of a single crystal with few impurities such as heavy metals is provided as a solid-state image sensor cover for sealing the package. A prevented imaging device is obtained.

In the present invention, the optical low-pass filter is preferably a birefringent plate.
In the present invention, in addition to the above-described effect, the birefringent plate constitutes a two-point separation optical low-pass filter. Therefore, the number of parts is small, the structure is simple, and the manufacture is facilitated. Therefore, the image pickup apparatus can be reduced in size, reduced in height, and reduced in price.

In the present invention, the optical low-pass filter includes a horizontal direction separation birefringence plate and a vertical direction separation birefringence plate, and is ¼ between the horizontal direction separation birefringence plate and the vertical direction separation birefringence plate. A wave plate is preferably arranged.
According to the present invention, in addition to the above-described effects, an optical low-pass filter that is separated by four points is constituted by two birefringent plates and a quarter-wave plate, so that an imaging device in which spatial high-frequency components are suppressed can be obtained. It is done.

In the present invention, the optical low-pass filter preferably includes a diffraction grating.
In the present invention, since the optical low-pass filter is constituted by the diffraction grating, the number of parts is small, the structure is simple, and the manufacture is facilitated. Therefore, the image pickup apparatus can be reduced in size, reduced in height, and reduced in price.

In the present invention, the diffraction grating has irregularities with a periodic cross-sectional shape, and includes a convex portion having a first refractive index and a concave portion having a second refractive index different from the first refractive index. The thickness of the convex portion and the thickness of the concave portion are preferably set such that the diffraction efficiency in the visible light region is substantially constant.
In this invention, the diffraction efficiency is kept substantially constant for each wavelength in the visible light region. Therefore, the diffraction grating functions as an optical low-pass filter that can extract a constant diffracted light intensity with respect to the incident light intensity at each wavelength, and an imaging apparatus that can faithfully reproduce the color tone of the subject in the visible light region can be obtained.

In this invention, it is preferable that the said convex part contains a silicon dioxide and the said recessed part contains a titanium dioxide or a tantalum pentoxide.
In the present invention, since a dielectric having excellent durability is used as a material for forming the diffraction grating, a highly reliable imaging device can be obtained.

In the present invention, it is preferable that the convex portion contains an ultraviolet curable resin or a thermosetting resin, and the concave portion contains titanium dioxide or tantalum pentoxide.
In this invention, since the convex part contains resin, it can respond to the price reduction of an imaging device.

In the present invention, it is preferable that the optical low-pass filter includes two diffraction gratings, a quarter-wave plate is disposed between the diffraction gratings, and the diffraction directions of the diffraction gratings are substantially orthogonal to each other.
In the present invention, since the diffraction directions of the two diffraction gratings are orthogonal to each other, a four-point separation optical low-pass filter is formed, and an image pickup apparatus having a higher-performance optical low-pass filter can be obtained.

In the present invention, the optical low-pass filter includes a birefringent plate and a quarter-wave plate, and the quarter-wave plate is disposed between the diffraction grating and the birefringent plate. It is preferable that the refraction direction and the diffraction direction of the diffraction grating are substantially orthogonal.
According to the present invention, an optical low-pass filter with a four-point separation in which the birefringence direction and the diffraction direction are substantially orthogonal to each other is configured, and an imaging apparatus having a higher-performance optical low-pass filter is obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
Fig.1 (a) is a schematic perspective view of the solid-state image sensor cover 40 and the imaging device 10 of this embodiment, FIG.1 (b) has shown the front sectional view in (a).
In FIG. 1, the imaging apparatus 10 includes a solid-state imaging device 1, a package 2, and a solid-state imaging device cover 40 that seals the package 2. The solid-state image sensor cover 40 includes a Z-cut quartz plate 3 and a birefringent plate 50.
As is well known, the Z-cut quartz plate 3 is a quartz plate that has been cut so that the normal of the principal surface of the quartz plate is 0 ° with respect to the Z-axis, which is the optical axis of the quartz. The refractive index (ns) of the Z-cut quartz plate 3 is 1.53, and birefringence (depending on the ordinary light refractive index and the extraordinary light refractive index) does not occur.
The solid-state image sensor 1 is housed in the bottom of a bowl-shaped package 2. The opening of the package 2 is closed by fixing the solid-state image sensor cover 40 to the opening by the adhesive 4, and the solid-state image sensor 1 is sealed.
A birefringent plate 50 as an optical low-pass filter 200 having a two-point separation function is provided on the light incident surface 30 of the Z-cut quartz plate 3.

For the solid-state imaging device 1, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), a CPD (Charge Priming Device), or the like can be used.
The package 2 may be formed by molding a ceramic, a thermosetting epoxy resin, a polyphenylene sulfide resin that is a thermoplastic polysulfone, or the like.

As the adhesive 4, a resin made of epoxy, vinyl acetate, acrylic, styrene, cellulose, polyamide, phenol, or the like can be used.
An antireflection layer can be provided on the surface of the birefringent plate 50 in order to prevent reflection on the surface. The antireflection layer is preferably a multilayer antireflection layer that suppresses reflection over the visible light region.

According to this embodiment, there are the following effects.
(1) Since the Z-cut quartz plate 3 made of a single crystal with few impurities such as heavy metals is provided as the solid-state image sensor cover 40 that seals the package 2, the solid-state image sensor 1 is less likely to generate α rays and damage to the solid-state image sensor 1. Thus, it is possible to obtain the solid-state image sensor cover 40 and the imaging device 10 that prevent the above-described problem.

  (2) Since the birefringent plate 50 constitutes the two-point separation optical low-pass filter 200, the number of components is small, the structure is simple, and the manufacturing can be facilitated. Therefore, the solid-state image sensor cover 40 and the imaging device 10 can be reduced in size, reduced in height, and reduced in price.

The second to sixth embodiments are different from the first embodiment in the configuration of the optical low-pass filter.
(Second Embodiment)
2A is a schematic perspective view of the solid-state image sensor cover 41 and the imaging device 100 of the present embodiment, and FIG. 2B shows a front sectional view of FIG.
The solid-state image sensor cover 41 includes a Z-cut crystal plate 3 and an optical low-pass filter 210. In the present embodiment, the optical low-pass filter 210 includes a horizontal direction separating birefringent plate 53, a vertical direction separating birefringent plate 90, and a quarter wavelength plate 8.
A quarter-wave plate 8 is disposed between the horizontal separating birefringent plate 53 and the vertical separating birefringent plate 90.

According to this embodiment, there are the following effects.
(3) Since the four-point separation optical low-pass filter 210 is constituted by the two birefringence plates of the horizontal direction separation birefringence plate 53 and the vertical direction separation birefringence plate 90 and the quarter wavelength plate 8, more space is provided. The solid-state image sensor cover 41 and the imaging device 100 in which the typical high-frequency component is suppressed are obtained.

(Third embodiment)
FIG. 3A is a schematic perspective view of the solid-state image sensor cover 42 and the imaging device 20 of the present embodiment, and FIG. 3B shows a front sectional view of FIG.
The solid-state image sensor cover 42 includes a Z-cut quartz plate 3 and an optical low-pass filter 220. In the present embodiment, the diffraction grating 5 is formed on the incident surface 30 of the incident light of the Z-cut quartz plate 3 as the optical low-pass filter 220. The diffraction grating 5 has irregularities with a periodic cross-sectional shape. In FIG. 3, the cross-sectional shape of the unevenness is a rectangular shape, but may be a trapezoidal shape or the like.
The diffraction grating 5 may be formed by etching the Z-cut quartz crystal plate 3 to form recesses, and a dielectric layer such as silicon dioxide is provided on the projections by a film forming means such as vapor deposition or sputtering. May be formed. Moreover, you may form an unevenness | corrugation using ultraviolet curable resin or a thermosetting resin.

The diffraction grating 5 functions as an optical low-pass filter 220 with two-point separation. The preferred grating height of the diffraction grating 5 is 0.1 to 1 μm, and the width and period of the convex part can be set according to the pixel period of the solid-state imaging device 1.
In FIG. 4, the diffraction efficiency I ₁ of the _first- order diffracted light of the diffraction grating 5 of the present embodiment is shown by a solid line. The horizontal axis represents the wavelength λ and the vertical axis represents the diffraction efficiency I.
The diffraction efficiency I ₁ of the _first- order diffracted light shows a mountain-shaped wavelength dependency having a peak at 600 nm in the visible light region.

  An antireflection layer can be provided on the surface of the diffraction grating 5 and the incident surface 30 in order to prevent reflection on the surface. The antireflection layer is preferably a multilayer antireflection layer that suppresses reflection over the visible light region.

According to this embodiment, there are the following effects.
(4) The diffraction grating 5 is integrally formed on the Z-cut quartz plate 3 to constitute one component, and the number of components can be reduced as the entire solid-state imaging device cover 42 and the imaging device 20. Therefore, the solid-state image sensor cover 42 and the imaging device 20 can be reduced in size, reduced in height, and reduced in price.

(Fourth embodiment)
FIG. 5A is a front sectional view of the solid-state imaging device cover 43 and the imaging device 60 of the present embodiment, and FIG. 5B is an enlarged front sectional view of FIG.
The solid-state image sensor cover 43 includes a Z-cut crystal plate 3 and an optical low-pass filter 230. This embodiment differs from the third embodiment in the configuration of the diffraction grating.
In FIG. 5A, the difference from the third embodiment is that the optical low-pass filter 230 provided on the incident surface 30 of the Z-cut quartz crystal plate 3 is a diffraction grating whose cross-sectional shape is periodic unevenness. The diffraction grating is that the convex portion 6 is made of a low refractive index material and the concave portion 7 is made of a high refractive index material.

  Below, with reference to FIG.5 (b), the relationship between the thickness of the convex part 6 and the thickness of the recessed part 7 is demonstrated. These thicknesses are set so that the diffraction efficiency I in the visible light region is substantially constant.

The ratio W / P between the width W of the protrusion 6 and the period P is set to 0.5.
The thickness of the convex portion 6 is d _L , the refractive index is n _L , the thickness of the concave portion 7 is d _H , and the refractive index is n _H.
Here, when the diffraction efficiency of the m-th order diffracted light of the diffraction efficiency is I _m , the diffraction efficiency I _m can be expressed by a function such as the expression (1) by P, W, and Γ.
I _m = f (P, W, Γ) (1)
Γ is a phase modulation amount.
Since the phase modulation amount Γ varies depending on the wavelength, in order to make the diffraction efficiency _{Im the} same value at different wavelengths, it is only necessary to compensate so that the phase modulation amount Γ does not change even if the wavelength changes.

The phase modulation amount Γ can be expressed as shown in Equation (2).
Γ = {(n _H −n _L ) d _H + (1−n _L ) (d _L −d _H )} / λ (2)
Here, the refractive index of the convex portion 6 at the wavelength λ ₁ is n _L1 , the refractive index of the concave portion 7 is n _H1 , the refractive index of the convex portion 6 at the wavelength λ ₂ is n _L2 , and the refractive index of the concave portion 7 is n. When _H2, the phase modulation amount gamma ₂ in the phase modulation amount gamma _1, and the wavelength lambda ₂ at a wavelength lambda ₁ of the formula (3), can be expressed as (4).
Γ ₁ = {(n _H1 −n _L1 ) d _H + (1−n _L1 ) (d _L −d _H )} / λ ₁ (3)
Γ ₂ = {(n _H2 −n _L2 ) d _H + (1−n _L2 ) (d _L −d _H )} / λ ₂ (4)
In order to make the diffraction efficiencies _{Im the} same at the wavelengths λ ₁ and λ ₂ , Γ ₁ = Γ ₂ suffices, so each condition may be set so as to satisfy Expression (5).
{(N _H1 −n _L1 ) d _H + (1−n _L1 ) (d _L −d _H )} / λ ₁ = {(n _H2 −n _L2 ) d _H + (1−n _L2 ) (d _L − d _H )} / λ ₂ (5)

Next, assuming the visible light region, the relationship between d _L and d _H is obtained.
The convex portion 6 is silicon dioxide, the concave portion 7 is tantalum pentoxide, the wavelength λ ₁ is 400 nm, and the wavelength λ ₂ is 700 nm. The refractive indexes of silicon dioxide and tantalum pentoxide at each wavelength λ ₁ and λ ₂ are as follows. When the wavelength λ ₁ = 400 nm, the refractive index of silicon dioxide is 1.495, the refractive index of tantalum pentoxide is 2.312, and when the wavelength λ ₂ = 800 nm, the refractive index of silicon dioxide is 1.467, five The refractive index of tantalum oxide is 2.158.
By substituting these values into equation (5), the result of equation (6) is obtained.
d _L = 2.87 d _H (6)

Therefore, if the thickness d _L of the convex portion 6 and the thickness d _{H of the} concave portion 7 are set so as to satisfy Expression (6), the diffraction efficiency I ₀ of the _0th- order diffracted light in the visible light region can be set to be substantially the same. it can. Also, the diffraction efficiency I _{1 of the first-} order diffracted light can be set substantially the same.
Here, considering the case of separation into two points, the zero-order diffracted light has a diffraction efficiency I ₀ of approximately 0, and the diffraction efficiency I _{1 of the first-} order diffracted light has only to be set to the maximum. = Γ2 = 0.5 is sufficient. Further, d _H and d _L are obtained by substituting Equation (6) into Equation (3), and d _H = 1872 nm and d _L = 5374 nm are obtained. The value obtained here is the optimum value at the wavelength λ ₁ = 400 nm. Therefore, in order to obtain the best efficiency in the visible light range, d _H and d _L were finely adjusted using the formula (2) and optimized within the wavelength range to be used. As a result, d _H = 1700 nm and d _L = 4878 nm were obtained.

FIG. 6 shows the result of simulating the relationship between the wavelength and the diffraction efficiencies I ₀ and I ₁ .
Before the optimization, the results when the thickness d _L = 5374 nm of the convex portion 6 and the thickness d _H = 1872 nm of the concave portion 7 which are the optimum values at the wavelength λ ₁ = 400 nm are shown by thin lines.
After optimization, the results when the thickness d _L = 4878 nm of the convex portion 6 and the thickness d _H = 1700 nm of the concave portion 7 that are further optimized within the wavelength range to be used are shown by bold lines.
From the simulation results shown in FIG. 6, by optimizing the thickness d _L of the convex portion 6 and the thickness d _{H of the} concave portion 7, the diffraction efficiency I ₁ in the visible light region can be set to be substantially the same, and the zero-order light can be set. It was confirmed that the peak of the diffraction efficiency I ₀ disappeared and the zero-order light was hardly diffracted.

In the case where silicon dioxide or tantalum pentoxide dielectric is used for the convex portion 6 and the concave portion 7, for example, the convex portion 6 and the concave portion 7 are formed as follows.
After a silicon dioxide film is formed on the Z-cut quartz plate 3 by film deposition means such as vacuum deposition or sputtering, the silicon dioxide film is etched and patterned by photolithography and etching to form convex portions 6, and the silicon dioxide film is formed. Titanium dioxide or tantalum pentoxide is formed in the removed portion by vacuum deposition or sputtering to form the recess 7.

When an ultraviolet curable resin is used for the convex portion 6, for example, a diffraction grating is formed as follows.
Titanium dioxide or tantalum pentoxide is formed on the Z-cut quartz plate 3 by vacuum deposition or sputtering. Next, etching is selectively performed by a photolithography method and an etching method. An ultraviolet curable resin is applied to the place from which titanium dioxide or tantalum pentoxide has been removed, and exposed to ultraviolet rays from the back side through the Z-cut quartz plate 3 to be exposed. In the portion where titanium dioxide or tantalum pentoxide is present, the transmittance of ultraviolet rays is reduced, and the ultraviolet curable resin is not sensitized. Therefore, the uncured ultraviolet curable resin can be removed using the stripping solution.

  In addition to the photolithography method and the etching method, a lattice may be formed using a mold having a nano-order pattern called a nanoimprint technique.

According to this embodiment, in addition to the effects of the third embodiment, there are the following effects.
(5) The diffraction efficiency I ₁ of the _first- order diffracted light can be kept substantially constant for each wavelength in the visible light region, and the diffraction efficiency I ₀ of the _zero- order diffracted light can be reduced. Therefore, the convex portion 6 and the concave portion 7 function as an optical low-pass filter 230 that can extract a constant diffracted light intensity with respect to the incident light intensity at each wavelength, and can faithfully reproduce the color tone of the subject in the visible light region. And the imaging device 60 can be obtained.

  (6) Since a dielectric having excellent durability is used as a material for forming the convex portions 6 and the concave portions 7, the solid-state imaging element cover 43 and the imaging device 60 with high reliability can be obtained.

  (7) When a resin is used as the low refractive index material, it is possible to cope with the cost reduction of the solid-state image sensor cover 43 and the imaging device 60.

(Fifth embodiment)
In this embodiment, the optical low-pass filter 230 obtained in the fourth embodiment is further combined with another diffraction grating to form a four-point separation optical low-pass filter 240.
FIG. 7A shows a schematic perspective view of the solid-state image sensor cover 44 and the imaging device 110 of the present embodiment. (B) is a front sectional view.
A quarter-wave plate 8 is disposed on the diffraction grating composed of the convex portions 6 and the concave portions 7, and a Z-cut quartz plate 31 on which the diffraction grating 51 is formed is further disposed thereon.
The diffraction grating 51 is composed of two types of refractive index materials, a convex portion having a low refractive index material and a concave portion having a high refractive index material, as in the diffraction grating formed of the convex portion 6 and the concave portion 7 formed on the Z-cut quartz crystal plate 3. Even if it consists of the comprised diffraction grating, it may consist of the diffraction grating comprised by one type of refractive index material like FIG. 3 of above-mentioned 3rd Embodiment.
Further, the diffraction grating 51 is arranged so that the diffraction direction thereof is substantially orthogonal to the diffraction direction of the diffraction grating composed of the convex portions 6 and the concave portions 7.

According to this embodiment, there are the following effects.
(8) Since the diffraction direction of the diffraction grating 51 and the diffraction grating composed of the convex part 6 and the concave part 7 are used orthogonally, a four-point separation optical low-pass filter 240 is formed, and a higher-performance optical low-pass filter 240 is formed. Can be obtained.

(Sixth embodiment)
In the present embodiment, the optical low-pass filter 230 obtained in the fourth embodiment is further combined with the birefringent plate 9 to form a four-point separation optical low-pass filter 250.
FIG. 8A shows a schematic perspective view of the solid-state image sensor cover 45 and the imaging device 120 of the present embodiment. (B) is a front sectional view.
A quarter-wave plate 8 is disposed on the diffraction grating composed of the convex portions 6 and the concave portions 7, and a birefringent plate 9 is further disposed thereon.
The birefringent plate 9 is disposed so that the birefringence direction thereof is substantially orthogonal to the diffraction direction of the diffraction grating composed of the convex portions 6 and the concave portions 7.

According to this embodiment, there are the following effects.
(9) The four-point separation optical low-pass filter 250 in which the birefringence direction and the diffraction direction are substantially orthogonal to each other is configured, and the solid-state image sensor cover 45 and the imaging device 120 including the higher-performance optical low-pass filter 250 can be obtained. .

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  The best method for carrying out the present invention has been disclosed in the above description, but the present invention is not limited to this. In other words, the present invention has been mainly described with reference to specific embodiments, but the materials, shapes, and other materials used for the above-described embodiments can be used without departing from the scope of the technical idea and object of the present invention. In detail, various modifications can be made by those skilled in the art. Accordingly, the description of the materials, shapes, and the like disclosed above is exemplary for ease of understanding of the present invention, and does not limit the present invention. Descriptions excluding some or all of the limitations are included in the present invention.

(A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 1st Embodiment of this invention, (b) is a front sectional view. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 2nd Embodiment of this invention, (b) is a front sectional view. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 3rd Embodiment of this invention, (b) is a front sectional view. The figure which shows the diffraction efficiency of 3rd Embodiment. (A) is a front sectional view of a solid-state image sensor cover and an imaging device concerning a 4th embodiment of the present invention, and (b) is an enlarged front sectional view. The figure which showed the relationship between a wavelength and diffraction efficiency. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 5th Embodiment of this invention, (b) is a front sectional view. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 6th Embodiment of this invention, (b) is front sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor, 2 ... Package, 3,31 ... Z cut crystal plate, 5,51 ... Diffraction grating, 6 ... Convex part, 7 ... Concave part, 8 ... 1/4 wavelength plate, 9,50 ... Birefringent plate DESCRIPTION OF SYMBOLS 10,20,60,100,110,120 ... Imaging device, 30 ... Incident surface, 40, 41, 42, 43, 44, 45 ... Solid-state image sensor cover, 53 ... Horizontal direction separation birefringence plate, 90 ... Vertical Direction separating birefringent plates, 200, 210, 220, 230, 240, 250... Optical low-pass filter.

Claims (18)

A solid-state image sensor cover that seals a package containing the solid-state image sensor,
The solid-state image sensor cover has a Z-cut quartz plate,
An optical low-pass filter is provided on the light incident surface of the Z-cut quartz plate. The solid-state image sensor cover according to claim 1,
The solid-state image sensor cover, wherein the optical low-pass filter is a birefringent plate. The solid-state image sensor cover according to claim 1,
The optical low-pass filter includes a horizontal separation birefringence plate and a vertical separation birefringence plate,
A solid-state imaging device cover, wherein a quarter-wave plate is disposed between the horizontal separating birefringent plate and the vertical separating birefringent plate. The solid-state image sensor cover according to claim 1,
The solid-state imaging device cover, wherein the optical low-pass filter includes a diffraction grating. In the solid-state image sensor cover according to claim 4,
The diffraction grating has irregularities with a periodic cross-sectional shape,
A convex portion having a first refractive index;
A recess having a second refractive index different from the first refractive index,
The thickness of the convex part and the thickness of the concave part are
A solid-state image sensor cover, characterized in that the diffraction efficiency in the visible light region is set to be substantially constant. In the solid-state image sensor cover according to claim 5,
The convex portion is silicon dioxide,
The concave portion includes titanium dioxide or tantalum pentoxide. In the solid-state image sensor cover according to claim 5,
The convex portion is an ultraviolet curable resin or a thermosetting resin,
The concave portion includes titanium dioxide or tantalum pentoxide. In the solid-state image sensor cover according to any one of claims 4 to 7,
The optical low-pass filter includes two diffraction gratings,
A quarter wave plate is disposed between the diffraction gratings,
The solid-state imaging device cover, wherein diffraction directions of the diffraction gratings are substantially orthogonal to each other. In the solid-state image sensor cover according to any one of claims 4 to 7,
The optical low pass filter includes a birefringent plate and a quarter wavelength plate,
The quarter-wave plate is disposed between the diffraction grating and the birefringent plate,
The solid-state imaging device cover, wherein a birefringence direction of the birefringent plate and a diffraction direction of the diffraction grating are substantially orthogonal to each other. A solid-state image sensor;
A package for housing the solid-state imaging device;
A solid-state image sensor cover for sealing the package;
The solid-state image sensor cover has a Z-cut quartz plate,
An imaging apparatus, wherein an optical low-pass filter is provided on an incident surface of the Z-cut quartz plate. The imaging device according to claim 10.
The optical low-pass filter is a birefringent plate. The imaging device according to claim 10.
The optical low-pass filter is
A horizontal separating birefringent plate and a vertical separating birefringent plate;
A quarter-wave plate is disposed between the horizontal separating birefringent plate and the vertical separating birefringent plate. The imaging device according to claim 10.
The optical low-pass filter includes a diffraction grating. The imaging device according to claim 13.
The diffraction grating has irregularities with a periodic cross-sectional shape,
A convex portion having a first refractive index;
A recess having a second refractive index different from the first refractive index,
The thickness of the convex part and the thickness of the concave part are
An imaging apparatus, wherein the diffraction efficiency in the visible light region is set so as to be substantially constant. The imaging device according to claim 14, wherein
The convex portion is silicon dioxide,
The concave portion contains titanium dioxide or tantalum pentoxide. The imaging device according to claim 14, wherein
The convex portion is an ultraviolet curable resin or a thermosetting resin,
The concave portion contains titanium dioxide or tantalum pentoxide. In the imaging device according to any one of claims 13 to 16,
The optical low-pass filter includes two diffraction gratings,
A quarter wave plate is disposed between the diffraction gratings,
The diffraction direction of the diffraction grating is substantially orthogonal to each other. In the imaging device according to any one of claims 13 to 16,
The optical low pass filter includes a birefringent plate and a quarter wavelength plate,
The quarter-wave plate is disposed between the diffraction grating and the birefringent plate,
The birefringence direction of the birefringent plate and the diffraction direction of the diffraction grating are substantially orthogonal to each other.

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